Focusing-finder



G. S. LALIN.

FOCUSING FINDER.

APPLICATION FILED MAY 31. 1918.

Patented Feb. 17, 1920.

3 SHEETS-SHEET 1- v APPLICATION FILED MAYSI, 191B- 1,3315269.

G. S. LALIN. FOCVUSING FINDER.

3 SHEETS-SHEET 2.

Fig. 4.

Patented Feb. 17, 1920.

G. S. LALIN. FOCUSING FINDER. APPLICATION FILED MAY 3 1, L918.

Patented Feb. 17, 1920.

3 SHEETSSHEET 3- Fjg. 15'.

Fig. 10.

4 m l I l J y y m 0 J J 0 0 0 0 I I M W In venfor- 0 hawk dag I compact without detracting through GEOBG SAMUEL LALIN, OF RASUNDA, SWEDEN.

FOCUSINGr-FINDER.

Specification of Letters Patent.

I Patented Feb. 17, 1920.

Application filed May 31, 1918. Serial No. 237,596.

To all whom it may concern.-

Be it known that I, GnoRG SAMunn LALIN, a subject of the King of Sweden, residing at Rasunda, in the Kingdom of Sweden, have invented a new and useful Improvement n Focusing-Finders, of which the following is a specification.

The invention relates particularly to focusing-finders for photographic cameras and it has for its objects to provide a folding focusing-finder which may readily be attached to a camera, as Well as means for adjusting the focusing-finder with respect to the camera.

My improvement further relates to means for reducing the volume of the focusingfinder, when folded, rendering it light and from its eiiiciency.

To these and other ends the invention consists in certain improvements and combinations of parts all as will be hereinafter described.

In the drawings: Figure 1 is a central, longitudinal, vertical section through an unfolded focusing-finder, constructed in accordance with my invention; Fig. 2 is the corresponding section through the foldedinstrument. Fig. 3 is a plan view showing the bottom of the folded instrument. Fig. 4 is a side elevation of the focusing-finder attached to a camera. Fig. 5 is a front elevation of the unfolded instrument. Fig. 6 is a detail of a mounting for fastening the wedge-shaped box of the unfolded focusingfinder to the camera; Fig. 7 is a detail of a mounting for fastening the lens of the focusing-finder to the camera. Fig. 8 is a horizontal section through the front plate and the side plates, showing a device for interlocking said plates. Fig. 9 is a section the lens holder. Fig. 10 shows a central, longitudinal vertical section through an unfolded focusing-finder of a second embodiment. Fig. 11 shows the corresponding section through the folded instrument. Fig. 12 is a front view of the lens holder of said second embodiment. Fig. 13 is the rear View of said lens holder, the lens and its mounting being removed. Fig. 14: is a top View of said lens holder showing the mounting of the lens in place. Fig. 15 is a mounting for fastening the lens of the focusing-finder of said second embodiment to the camera.

In carrying out my invention I provide in general a rectangular frame between the upper edges of which a focusing-screen is mounted and to the rearv lower edge of which a plate is connected by means of hinges, said plate carrying'a reflecting mirror. To said plate a system of plates is connected by means of hinges and arranged in such manner that the focusing screen and the plates may together he made to form a wedge-shaped box, or the plates may be laid flat on top of one another. The said wedgeshaped box is connected by means of a bellows to the front of the instrument in which there is attached a lens of equal focal length as that of the lens of the camera with which the instrument is to be used.

Referring to the drawings and particularly to Fig. 1 thereof, for a more detailed description of these and other parts, and of their operation, 1 is a rectangularframe provided at its upper four edges with hinges connecting plates 25 and 26, which serve as a guard against outside light on the image recording focusing screen 2, mounted in the upper part of said frame. In order to secure said light guard in its upright position and at the same time to prevent the entrance of light at the corners between the different plates, I provide the plates 25 on each upright edge with a flange or bend, as shown in Fig. 4-, and construct the hinges so that said plates Will press against the upright edges of the plates 26. The late 3, carrying the mirror 5, is connecte by means of hinges 4 to the frame 1. To the plate 3 side plates 7 are connected by means of hinges 6 and the plate 9 by means of hinges 8'. I prefer to make a bend in the plate 3 at 68 to provide sufiicient. space between the mirror and the plate 9 to accommodate the side plates 7 in folded condition, as illustrated in Fig. 2. For preventing the entrance of light at the corners between the plates 7 and the plate 9 I prefer to bend the upright edges of plate 9 as shown in Fig. 8.

Portions 10 of the side plates 7 project beyond the hinges 6 and are provided with hooks 11 of flexible metal wire supporting the wedge shaped box of the focusing-finder on the camera, as will be described here below. In unfolded condition of the focusing-finder the front of the frame 1 is supported on the plate 9, said plate being locked in position by forcing the side plates 7 past the springs 15, Fig. 8, secured to the plate 9, thus rendering the box rigid. The frame or plate 9 is connected to the lens holder 17 by means of the bellows 16. The lens holder 17 is provided with a hook 21. Fig. 5, of flexible metal wire, supporting the front of the focusing-finder.

Devices which I prefer to employ in the present instance for adjusting the lens 18 consist of corresponding threads 20 in the lens holder 17 and on the lens mounting 19, hence by turning the lens it may be moved in the direction of its axis.

Devices which I prefer to employ for attaching the focusing-finder to the camera with which it is to be used, consist in general of two mountings, permanently secured to the camera. The mounting 12, Fig. 6, is to be secured to the camera boX and the mounting 23, Fig. 7 is to be secured to the front of the camera, as illustrated in Fig. 4, 13 being a typical camera of ordinary construction. The focusing-finder will now easily be attached to the camera by pressing the hooks 11 down into the sockets in the mounting 12 and the hook 21 into the slotted hole 22 in the mounting 23.

Detaching the focusing-flnder from the camera and folding it is accomplished by pulling the hook 21 out of the mounting 23 and the hooks 11 out of the mounting 12, then by pressing the side-plates 7 inward these plates will be forced over the springs 15 and will be flapped dow n'on top of the mirror 5. Now the bellows 16 will be folded, and said bellows together with the lens, the lens-holder and the front plate 9 are flapped down on top of the side plates 7. The plates 25 and 26 constituting the light guard are to be flapped over one another on top of the focusing screen 2. By turning the rear plate 3 against frame 1 and forcing the hinges 8 beyond a hook or a lug 24 provided on the inside of the frame 1 the focusingefinder will be closed. The casing of the folded focusingfinder thus consists of the light guard, the frame 1 and the rear plate 3 as shown in Figs. 2 and 3.

Figs. 10 and 11 illustrate a second embodiment of the focusing-finder on which the light guard 65 and 66, the focusing screen 52, the frame 51, the plate 53, the mirror 55, and the side plates 57 with their projections 60 and hooks 61, and the combination of these parts are substantially similar to the corresponding parts and the combination of the same in the embodiment above described. The inside of the frame 51 is provided with a bent plate 27 hearing against the plate or frame 59. In the present instance I obtain rigidness of the wedgeshaped box by forcing the upper edges of the plates 57 against a lug 28 provided on the plate 59. Said plate 59 is combined with the front part of the focusing-finder by means of the bellows 46.

Devices which I prefer to employ in the present instance for adjusting the lens of the focusing-finder relatively to the lens of the camera consist in general of a mounting provided with thread-shaped flanges pressed by means of springs against hooks secured to a ring which may be turned by an external button. Referring to the drawings the plate 31, Fig. 12, is provided with a round opening 33 for entrance of the light to the lens 48 and a circular slot 32 through which the external button. 40 is connected to the ring 37 journaled in four guides 39 on the back of said plate 31, Fig. 13. By means of brackets 34 secured to the mounting 29 it is guided on the pins 35 secured to the plate 31, Figs. 13 and 14. By means of springs 36 the thread-shaped flanges 30 on the cylindrical surface of the mounting 29 are pressed against the hooks 38 secured to the ring 37. It will be understood that by this arrangement the size of the focusing-finder, when folded, will not be dependent upon whether the lens has been placed more or less distant from the plate 31 by means of the button 40.

Fig. 15 illustrates a suitable mounting 42 to be permanently secured to the camera front and used for attachment of. the front of the alternative construction of the focusing-finder above described. projection 41, Figs. 10 and 12, of the plate 31 is to be pressed down into the slot 43 of said mounting 42. r p

The focusing-finder is to be adjusted when attached to the camera, the adjustment being effected by focusing the camera by means of its focusing scale on an object whose distance from the camera is known, or on so called infinite distance, whereupon the lens of the focusing-finder is to be moved back or forth by the means above described until the image on the focusing screen is sharp. This having been done for one certain distance the image will also appear sharp for any other distance, as the focal length of the lens of the focusing-finder is the same as that of the lens of the camera.

I claim:

1. In a focusing-finder, the combination of a frame, a focusing screen secured in said frame, a reflecting mirror hinged to said frame, a bellows connected to said reflecting mirror, and a lens supported in said bellows.

2. In a focusing-finder, the combination of a frame, a focusing screen secured in said frame, a reflecting mirror hin ed to said frame, plates hinged to said re ecting mirror, a frame hinged to said reflecting mirror, a bellows attached to said frame, and a lens supported in said bellows.

3. In a focusingfinder, the combination of a frame, a focusing screen secured in said frame, a reflecting mirror hin ed to said frame, plates hinged to said ret fecting mirror, means on said plates for securing the focusing-finder to a camera, a frame hinged to said reflecting mirror, a bellows attached The corrugated to said frame, and a lens supported in said bellows.

4. In a focusing-finder, the combination of a frame, a focusing screen secured in said frame, a reflecting mirror hinged to said frame, a frame hinged to said reflecting mirror, a bellows attached to said frame, a lens supported in said bellows, and means for adjusting the lens in its axial direction in said bellows.

5. In a focusing-finder, --the combination of a frame, a focusing screen secured in said frame, a reflecting mirror hin ed to said frame, a frame hinged to said re ecting mirror, a bellows attached to said frame, a plate provided with an opening attached to said bellows, a lens, means on said plate for supporting the lens and for guiding the same toward and away from said opening, screw threads at the periphery of said lens, and means rotatably connected with the said plate and engaging said screw threads, substantially as and for the purpose described.

6. In a focusing finder, the combination of a frame, a focusing screen secured in said frame, a reflecting mirror hinged to said frame, a bellows adapted to be folded in a position substantially parallel with said screen, and a lens supported in said bellows.

GEORG SAMUEL LALIN. 

